Overview
What is keratitis Eye?
Cornea is the outer front layer of the eyeball. Cornea plays a role in the refraction of the eye, 2/3 portion of refractive power is provided by the cornea. It is a highly transparent structure however the cornea is richly supplied with nerves. Any damage to the cornea may give excruciating pain to the patient.
Any damage or inflammation to the corneal outer or inner surface is labeled as keratitis. It is a painful condition and consists of a long list of causes. Some of the causes include various types of bacteria, viruses, fungus, and certain autoimmune and neuropathic conditions. The article will focus on the causes, symptoms, signs, diagnosis, and management plan of keratitis eye.
Causes
Keratitis Causes
Bacterial keratitis: Bacterial keratitis is caused by various forms of gram-positive and gram-negative bacteria. The bacterial invasion occurs when a breach is present on the surface of the cornea. However, there are certain bacteria that can invade an intact corneal surface such as Neisseria, Hemophilus, and Cory bacteria. The lesion of bacteria is mostly composed of plaque-like and associated hypopyon and anterior chamber activity is present.
Fungal keratitis: Fungal keratitis is the most common cause of keratitis with vegetative trauma such as leaves and sticks. It is signified by grey corneal infiltrates with satellite lesion in the peripheral area of the main lesion. Most of the common causes of fungal keratitis include candida and filamentous fungi.
Viral keratitis: The common causes of viral keratitis include herpes simplex virus and herpes zoster virus. The cornea is seldom involved in herpes zoster. However, in the herpes simplex virus, the corneal epithelium and stroma are commonly involved. The characteristic features of stromal keratitis include keratic precipitates with overlying stromal haze and infiltrate giving Weiss ring appearance. In epithelial keratitis, a branching pattern of lesion with blub-like endings are a common finding. They can be easily stained with fluorescein.
Interstitial keratitis: Interstitial keratitis is a type of keratitis without prior involvement of epithelium and endothelium. It can occur in various types of diseases such as syphilis, tuberculosis, Lyme disease, and sarcoidosis. Syphilis disease is a common type of interstitial keratitis.
Protozoal keratitis: It includes invasion of the cornea with protozoa named acanthamoeba. It is commonly found in tap watering. Tap water when used for washing and cleansing contact lenses can lead to protozoal keratitis. The path gnomic sign of fungal keratitis is perineural infiltrates. The infiltrates may enlarge and form ring abscesses.
Helminths keratitis: It includes keratitis with organisms such as onchocerciasis.
Bacterial hypersensitivity: Hypersensitivity to organisms such as staphylococcus aureus may arise with associated conjunctivitis. Antibodies are formed and may lead to infiltrate deposition in the cornea.
Neurotropic keratitis: Cornea is supplied by the trigeminal nerve. Any damage to the nerve may result in neurotropic keratitis. The corneal sensation may be reduced In this condition.
One of the other classifications for keratitis eye is as followed
What causes infectious keratitis eye?
Infections keratitis. It includes bacteria, viruses, fungus, and acanthamoeba.
What causes noninfectious keratitis eye?
Traumatic keratitis. It includes trauma to the cornea with the invasion of the cornea by organisms. The most common cause is fungal keratitis.
Contact lens keratitis: It is associated with contact lens users who use tape water for cleansing.
Autoimmune keratitis: It is caused due to hypersensitivity reaction to surface antigens such as staphylococcus aureus.
Risk Factors
What are the risk factors for developing keratitis eye?
These includes
- Keeping poor hygiene
- Constantly rubbing eyes
- Using tape water for cleansing contact lenses
- Swimming in dirty pools
- Using steroids for a prolonged duration
- Any insulting trauma to the eye
- Any surgery causing damage to the nerve supply of the cornea or nerves playing role in the blinking of the eyelids
- Weak immune system
- Dry eyes for a prolonged period of time
Symptoms and Signs
What are the signs and symptoms of keratitis?
The symptoms of keratitis eye include
- Pain in the eye or periocular region
- Redness of conjunctiva
- Watering
- Irritation
- Photophobia/ sensitivity to light
- Foreign body sensation
- Difficulty in opening eye
Diagnosis and Tests
How is keratitis diagnosed?
The identification of keratitis eye includes various tests.
History taking: The health professional will take a detailed history about history of any trauma, contact use, and drug history, and the immune status of the patient is assessed.
Slit lamp exam: It includes a detailed examination of the cornea and its layers as well as the limbal area, conjunctiva as well as eyelids are also examined.
Fluoresceine stain: The stain is used as a marker for certain conditions such as the herpes virus. It highlights the abrasions on the surface of the cornea,
Gram and Gamesa stain: Samples are taken from the lesion area and gram Gamesa staining is done. It is used to categorize the disease cause on the basis of penetration of gram stain.
Culture medias: Culture media are also helpful in the identification of the cause. Some of the culture medians includes
- Blood agar: the specificity of blood agar is for most of the bacteria except Neisseria and Hemophilus.
- Chocolate agar: Its specificity is for fastidious bacteria and Neisseria and Hemophilus.
- Sabourad agar: It is commonly used for fungi.
- Lowenstein Jenson stain: it is useful for Nocardia and Mycobacterium.
- Non-nutrient agar seeded with E. coli: It is specific for acanthamoeba.
- Cooked meat broth: It is used for anaerobic organisms such as Propionibacterium acne.
- Brain heart infusion: It is useful in difficult situations such as streptococci and meningococci.
Biopsy: In resistant cases and not responding to the therapy, the biopsy is taken for a definite diagnosis.
Treatment and Management
How is keratitis treated?
The treatment depends upon the cause of the lesion.
Bacterial Keratitis Treatment
The first line of therapy for bacterial keratitis is quinolones, which include ciprofloxacin, moxifloxacin, besifloxacin, etc. In certain resistant cases, a combination of two drugs or fortified antibiotics are prepared from cephalosporin and macrolides.
Fungal Keratitis Treatment
Fungal keratitis is treated with topical drugs which includes natamycin, amphotericin, clotrimazole, voriconazole, etc. in the lesion with limbal area involvement or risk of endophthalmitis are treated with topical and oral medications for at least three months.
Viral Keratitis Treatment
The treatment of viral keratitis depends upon the location of the lesion. In geographical ulcer with the involvement of epithelium, antivirals are used alone. However, lesion involving the stroma are treated with steroids and anti-viral drugs for a period of three months.
Interstitial Keratitis Treatment
The treatment strategy mainly depends upon the cause.
Protozoal keratitis: In contact lens related keratitis eye, specific drugs for acanthamoeba are used that includes polyhexamethylbiguinides and chlorhexidine. However, in resistant cases, a combination of two drugs can be used.
Bacterial hypersensitivity: This includes marginal keratitis and phylctenulosis. The treatment option for both conditions are steroids.
Neurotrophic keratopathy:For neurotrophic keratopathy the cause of the neuropathy is removed or else topical drugs like lubricants or steroids are used.
Prevention
How to prevent the development of keratitis?
A few steps can be followed in order to avoid the development of keratitis eye. These includes
- Keeping good hygiene by washing your hands before touching the eye.
- Thoroughly washing the eyelid margins every day with a non-toxic shampoo.
- Care should be taken in handling contact lenses, and the label should be read carefully.
- Tape water should not be used for the cleaning purpose of contact lenses.
- Avoiding swimming in dirty or contaminated water.
- Using protective glasses in the workplace.
Outlook and Prognosis
What can I expect if I have keratitis?
The prognosis of keratitis eye depends upon the cause and how regularly the medications have been used. Timely recognition and opting for the treatment well on time can have a better prognosis. However, if the treatment is delayed and instructions for the use of medication are not followed, it can result into vision loss permanently or lead to scaring of the cornea.
When to see a doctor?
If you experience pain, redness or watering and blurring of vision or if there is a history of trauma to the eye, immediate consultation should be taken by a health professional.
Conclusion
Keratitis is one of the visions threatening condition. However timely recognition of the condition and seeking immediate help can reduce the chance of permeant vision loss.
FAQ’s
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What is the main cause of keratitis?
The main cause of keratitis in contact lens user is protozoal infection e.g., acanthamoeba. However, in those people working in the field the most common cause is fungal infection. Thus, the cause varies from person to person.
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How do you know if keratitis is healing?
The reduction in pain and improvement in vision are few specific signs for improvement.
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What is the fastest way to get rid of keratitis?
Timely recognition and proper use of prescribed medications by the health professional cause the keratitis eye to heal sooner.
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Can keratitis heal on its own?
It is less likely for the keratitis to heal on its own. However, the type of keratitis eye such as marginal keratitis can heal on its own but will take a prolong duration of time.
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Can keratitis spread to other eye?
As keratitis is an infectious condition any trauma to the other eye or abrasions on the surface of the eye can result in the infection of the other eye.
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Does keratitis always cause blindness?
No, timely recognition and early treatment will not cause a patient get blind.
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Is keratitis eye an emergency?
Yes, it is an eye emergency because if left untreated for a short duration of time will cause corneal thinning and melting leading to blindness.
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How long keratitis last?
It depends upon the cause and time of start of medical therapy. Some benign condition such as marginal keratitis will resolve in a week or two while fungal and bacterial condition can take over a month.
References
- Kashiwabuchi RT, de Freitas D, Alvarenga LS, et al. Keratitis: A Review of Diagnosis and Treatment. Revista Brasileira de Oftalmologia. 2017;76(5):286-291. doi:10.5935/0034-7280.20170064
- American Academy of Ophthalmology. Corneal Infections (Keratitis). https://www.aao.org/eye-health/diseases/corneal-infections-keratitis-2. Accessed March 19, 2023.
- Centers for Disease Control and Prevention. Parasites – Acanthamoeba keratitis. https://www.cdc.gov/parasites/acanthamoeba/keratitis.html. Accessed March 19, 2023.
- Wu S, Li R, Yao Y, et al. Clinical characteristics and visual outcomes of fungal keratitis in a tertiary hospital in Eastern China. BMC Ophthalmology. 2021;21(1):201. doi:10.1186/s12886-021-02033-4
- Suresh S, Wong TY. Diagnosis and Management of Bacterial Keratitis. Clinical Ophthalmology. 2016;10:117-127. doi:10.2147/opth.s74799
